Armstrong's illness forced the pop-punk group to cancel their show in Bologna, Italy, on Sunday, and bandmates Mike Dirnt and Tre Cool released a brief video message to fans, apologizing for missing the European tour date (above).

Cool said of the cancellation, "We're beyond devastated, we're as sad as you guys are - Billie's extremely upset about it, and we'll see you very soon."

Both rockers emphasized that the group would return to the Italian city as soon as they can. In the meantime, they'll rock the house on MTV Thursday.